The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Many electronic devices, for example, telephones, answering machines, fax machines and computers, may include a mechanism for recording or playing audio. In these systems, the audio signal typically includes a desired signal component and a noise component. In some situations, the effect of the noise component can be significant and can detract from the overall audio experience. When the desired signal component of the audio signal is not present, such as during a period of silence, the device playing the audio signal will only reproduce the noise component. Thus, the noise component may be especially noticeable during such periods of relative silence.
During playback, it is generally desirable to have the noise level be as low as possible. Furthermore, the noise component may have a specific or dominant feature, such as a constant tone at a given frequency, which may be particularly bothersome to a user listening to the playback of the audio signal.
Electronic systems are generally designed to control or eliminate noise. It is sometimes necessary, however, to control noise during playback after a system has captured noise during the recording process, e.g., leaving a message on an answering machine while in a noisy environment. Furthermore, fully designed systems may be susceptible to the effects of noise at specific frequencies because of other design considerations, which makes it impractical to control or eliminate noise at the design stage.